Current nutritional guidelines restrict the consumption
of saturated fats, such as those found in butter, cream, fatty cuts of
meat, among others and encourage the consumption of polyunsaturated fats (found
in fish and plant sources), since the former were thought to be linked to
increased risk of heart disease.
A new study conducted in March 2014 challenges
this theory and finds that the evidence for these guidelines may not be
definitive. It does not support high consumption of polyunsaturated fats such as
omega 3 or omega 6 fatty acids in order to reduce coronary heart disease. The
study results were published in the journal
Annals of Internal Medicine.
The study was led by the University of Cambridge, which analyzed the
existing studies and randomized trials on fatty acid intake and risk of
coronary heart disease. The results of the research do not support the
guidelines, which restrict the consumption of saturated fats in order to
prevent heart disease.
For
the purpose of the study, fatty acid exposure included levels of fatty acid
biomarkers and amount of fatty acid intake, which was estimated by diet
questionnaires.
Coronary
disease was defined as fatal
or non-fatal heart attack, angina, coronary insufficiency and sudden cardiac
death.
The researchers studied data from 72 unique studies
with over 600,000 participants from 18 countries. These studies considered the intake of total saturated
fatty acid, total monounsaturated fatty acid, total long-chain-3 polyunsaturated
fatty acid, total-6 polyunsaturated fatty acid and total trans-fatty acid
intake.
They concluded that the total saturated fatty acid was not associated
with coronary disease risk in the observational studies both when measured in
the diet or in the bloodstream as a biomarker. They also did not find any
significant relation between consumption of total monounsaturated fatty acids
and increase in coronary risk. However, they found that individual subtypes of
polyunsaturated fatty acids, such as long-chain omega 3 and omega 6 fatty acids
were linked to heart risk differently.
When researchers
looked at studies with saturated fatty acids, they found weak links between
bloodstream levels of palmitic acid and stearic acid and heart disease, but it
was seen that blood levels of the dairy fat margaric acid could significantly
reduce heart risk.
They also studied trials,
which tested the effects of adding omega 3 and omega 6 supplements to diets.
These trials reportedly did not see any benefit in reducing risk of coronary
disease.
The
following were reported to be some limitations to this study:
- For the studies based on dietary intake, the
period of assessment of diet time was unclear.
- The amount of fat consumption i.e., fat
consumption per day between people in the top third as compared with people in
the bottom third was unclear.
- The
results may not be applicable to healthy subjects, since some of the studies
involved people with a pre-existing health condition.
Dr. Rajiv Chowdhury from
Cambridge University, who is the lead researcher said: "These are
interesting results that potentially stimulate new lines of scientific inquiry
and encourage careful reappraisal of our current nutritional guidelines.
Cardiovascular disease, in which the
principal manifestation is coronary heart disease, remains the single leading
cause of death and disability worldwide. In 2008, more than 17 million people
died from a cardiovascular cause globally. With so many affected by this
illness, it is critical to have appropriate prevention guidelines which are
informed by the best available scientific evidence."
Thus even though the current NHS guidelines suggest
that men should not consume more than 30g of saturated fat per day and women
not more than 20g, the above study has shown that diets which are low in
saturated fat do not lower cholesterol or prevent heart disease.
Dr.
Frank Hu, a professor of nutrition and epidemiology at the Harvard School of
Public Health, said the results of the study should not be mistaken as a means
to eat more butter, cream and other foods, which are rich in saturated fat. He
added "Looking at individual fats and other nutrient groups in isolation could
be misleading, because when people cut down on fats they tend to eat more
bread, cold cereal and other refined carbohydrates that can also be bad for
cardiovascular health."
Science is constantly
changing. For years, we believed that saturated fat is a nutritional demon, but
the current study just shows us otherwise. Till more studies are conducted to
present conclusive evidence in this favor, choose what you put on your plate
wisely. Remember a healthy outside starts from the inside. Eat to nourish your
body. After all you are worth more than you realize!
Careers
